Updated OS X pid_exists to use kill() instead of iterating process list since  this is faster and more elegant (and avoids needing a special case for PID 0).
Updated OS X pid_exists to use kill() instead of iterating process list since 
this is faster and more elegant (and avoids needing a special case for PID 0).



git-svn-id: 9f18dd852162ff6c59c5533c0914e9cf81af9e7c@167 d8a29897-7e4b-0410-a74a-8bb4c295346f

elventear/psutil,elventear/psutil